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Password Protect Your System

A passord won't relly protect anything unless it prevents snoops from using your hard disk, but it can discourage casual users who shouldn't be there.

You shouldn't load password programs from AUTOEXEC.BAT, since fast-fingering users can pound out Ctrl-C and abort AUTOEXEC.BAT before it runs the program. Loading from CONFIG.SYS is better, since you normally can't abort CONFIG.SYS.

Jeff Prosise wrote a slick little PASSWORD.SYS program in July 1990 issue of PC/Computing that loads for CONFIG.SYS and won't let the system start untill the proper password is entered. It stores the password in plaun ASCII text, and any user can boot off a floppy and get around it, but it does keep honest people out, especially after a tiny patch.

Jeff's program is terrific, but it's named PASSWORD.SYS and it puts a PASSWORD: promt onscreen. Someone trying to break into your system would see that and look for ways to get around it.

Giving Jeff's programm a less obvious name and changing the prompt makes PASSWORD.SYS even better. Rename it something like MATHCHIP.SYS (as in the example below) or VGA_SCRN.SYS, then replace the PASSWORD: promt with something more diabolical. I substituted ERROR 1101, whih sounds binary and evil.

To se the modified version of Jeff's proggram in action, create the following PROSISE.SCR file:

E 100 FF FF FF FF 00 80 2B 00
E 108 36 00 45 52 52 4F 52 20
E 110 31 31 30 31 00 06 00 61
E 118 62 63 64 65 66 20 20 20
E 120 20 20 20 20 20 20 20 00
E 128 00 00 00 2E 89 1E 27 00
E 130 2E 8C 06 29 00 CB 9C 50
E 138 53 51 52 56 57 55 1E 06
E 140 0E 1F C4 3E 27 00 26 80
E 148 7D 02 00 75 12 E8 20 00
E 150 26 C6 45 0D 00 26 C7 45
E 158 0E 00 00 26 8C 4D 10 26
E 160 C7 45 03 00 01 07 1F 5D
E 168 5F 5E 5A 59 5B 58 9D CB
E 170 FC 33 DB B4 02 33 D2 CD
E 178 10 BE 0A 00 B9 0A 00 51
E 180 AC B4 0E CD 10 59 E2 F7
E 188 57 06 0E 07 FC BE 17 00
E 190 BF 1F 00 C6 06 14 00 00
E 198 B4 00 D 16 3C 08 75 0E
E 1A0 80 3E 14 00 00 74 F1 FE
E 1A8 0E 14 00 4F EB EA 3C 0D
E 1B0 74 0E 80 3E 14 00 08 74
E 1B8 DF FE 06 14 00 AA EB D8
E 1C0 8B 0E 15 00 E3 C7 3A 0E
E 1C8 14 00 75 C1 BF 1F 00 F3
E 1D0 A6 75 BA 07 5F C3
N MATHCHIP.SYS
RCX
D6
W
Q

Make sure you leae a blank after the final Q, the rev up our coy of DEBUG and type:

DEBUG < PRSISE.SCR

This will create a file clled MATHCHIP.SYS. Put MATHCHIP.SYS in your \DOS subdirectory, and make the fisrt line of your CONFIG.SYS file:

DEVICE=C:\DOS\MATHCHIP.SYS

The pasword used in MATHCHIP.SYS is "abcdef," but it's easy to change. Jeff built in a way to make your own password up to eight characters long. A byte at location 115 stores the number of characters in hex notation, and the actual password begins at address 117.

To change the password to MOONBEAM, for example, type:

DEBUG MATHCHIP.SYS
E 117 'MOONBEAM'
E 115 8
W
Q

To give yourself a short password like PCC, type:

DEBUG MATHCHIP.SYS
E 17 'PCC'
E 115 3
W
Q

Note that psswords are case sensitive, so entering "pcc" won't work if you've patched te program to accept PCC. Also, as Jeff pointed out in the original article, some systems won't be able to handle this program with a copy of your old CONFIG.SYS. If you try the program on your hard disk and you have trouble, boot of the floppy and copy the old CONFIG.SYS from the floppy to the root directory of the hard disk.

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